Otter (Lutra lutra)

A mainly nocturnal mammal, of the mustelid family.

Description: Length: 110-120cms (43-47''). Weight: 8-10kgs (17-22lbs)
Males are larger than females. They have shiny brown fur, flattened heads, small ears, webbed feet with claws and their tails are thicker at the base, tapering to a point.

Their thick fur is waterproof and very warm. It has stout guard hairs up to 20mm long to make it waterproof and a finer layer of fur underneath for insulation. They are excellent swimmers and divers and to make it easier their ears and nostrils close when underwater!

Habitat: Well vegetated river banks, with an extensive home range, up to 30km along the river.

Diet: Daily energy requirements are between 12-15% of their body weight (1-1.5kgs). In order to meet this they have an eclectic diet, comprised of whatever is available, whether it be crayfish, bullheads, eels, perch or salmonids (trout and salmon).

Breeding: Breeding season is February to April. There is a gestation period of 62 days and litters typically consist of 2 or 3 cubs, but range from 1 to 5.

At birth, otters only are about 12cms long and weigh 100-150g. They are born blind with grey hair but after five weeks they open their eyes and begin crawling unsteadily around. They then weigh about 800g.

Weaning occurs at seven weeks but they do not leave the den for a further two weeks. The female trains her cubs to swim when they are about ten weeks old, but they remain with her until the following spring.

Lifespan: Up to ten years, although there is a 50% mortality rate at three years.

Otters were once one of the most threatened European mammals. Common causes of death include road deaths, poisoning, and unintentional trapping in fish traps. The original decline is thought to have been caused by the widespread use of dieldrin, DDT and other organochlorine pesticides. Since these pesticides were banned in 1989 UK otters have staged a remarkable recovery.

They are protected under the Wildlife and Countryside act (1981) and the European Habitats Directive (1992).